Greco
gas mixer apparatus



y 13, 1965 G. GRECO 3,194,264

GAS MIXER APPARATUS Original Filed Sept. 26, 1955 United States Patent 3,194,264 GAS MlXER APPARATUS Guido Green, Milan, Italy, assignor to Montecatini, Societa Generale per llndustria Mineraria e Chiniiea, Milan, ltaly, an ltalian corporation Application Sept. as, 1956, Ser- No. 612,134, new Patent No. 3,052,288, dated Sept. 4, 1962, which is a division of application Ser. No. 536,530, Sept. 26, 1.055, new hatent No. 2,859,103, dated Nov. 4, P358. Blvided and thisapplication Feb. 23, 1967., Ser. No. 175,240 Claims priority, application ltaly, Sept. 28, 1954,

. Patent 525,183

2 Claims. (Cl. 137-556) This application is a division of patent application Serial Number 6l2,l84 filed September 26, 1956, now Patent No. 3,052,288 granted September 4, 1962, which is in turn a division of Serial Number 536,510, filed September 26, 1955, now Patent No. 2,859,103 granted November 4, 1958.

The present invention relates to the production of synthesis gas, that is, carbon monoxide and hydrogen, by means of the partial combustion of methane, or other gaseous aliphatic hydrocarbons, with oxygen in the absence of catalysts, being particularly directed to devices for carrying out this process.

In his Italian Patent No. 446,318 the applicant has described a process for the production of synthesis gas from gaseous aliphatic hydrocarbons and oxygen. In a first stage of that process the two gases are reacted with each other in form of a swirling mixture and thereafter, in a second stage, the gas mixture is further reacted by means of the heat set free in the first reaction stage and in the presence of known catalysts. For this purpose, the hydrocarbon gas and the oxygen are introduced into the combustion chamber by means of nozzles. This manner of introduction, which produces a strong swirling motion or" the gases, and the arrangement of the first stage reaction chamber adjacent to a catalysis chamber provided for the second stage of the reaction, permits the use of practically pure and undiluted hydrocarbons and oxygen in contrast to previously described processes of this type. Moreover, the process avoids the formation of undesirable gas black. It was the formation of gas black and the incomplete conversion of methane which, until the said invention, caused the failure of every attempt to employ practically (95-100%) pure hydrocarbons, without the addition of any inert gases or steam in carrying out the process illustrated by the following known equations.

First stage (exothermic):

Second stage (endothermic, supported by the heat liberated in first stage):

It is the principal object of this invention to improve upon the foregoing process by furnishing a method of operation which, aside from avoiding the formation of gas black and reducing the amount of methane in the final gaseous reaction mixture to a minimum, represents a substantial improvem nt in (a) eliminating the use of catalysts, (b) demanding substantially little reactor space, (c) not requiring the supply of outside heat and (d) requiring unexpectedly low reaction temperatures (about 900 C.) While using 95-l00% pure hydrocarbon, without the addition of any inert gas or steam.

It is another object of the invention to furnish devices by which the improved process of producing synthesis gas may be carried out.

ice

The invention will best be understood from the following description of several preferred embodiments of the herein claimed devices taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic sectional view of a burner (outlet tube),

FEGS. 2 and 2' are cross-sectional views on the lines AA and BB, respectively, in FIG. 1,

FIG. 3 is a schematic sectional view of one embodiment of a pre-mixer of the present invention,

PEG. 4 is a cross-sectional view on the line CC in FIG. 3,

PEG. 5 is a schematic sectional view of another embodiment of a pro-mixer of the present invention, and

FIG. 6 is a cross-sectional view on the line DD in FIG. 5.

In the process carried out in accordance with the present invention a very complete pro-mixing of the reaction gases, such as (IE and O is executed outside the reaction chamber. This is attained by impacting the respective gas streams upon each other. For this purpose the effective components of the kinetic energies of the two gases, or expressed differently, the aliquots of the kinetic energies of the gas flow rates relating to the opposite direction components of the velocities of the two reacting gases, should be equal, and preferably of the order of 100-200 kgnL/Nm. of CH, (Nm. representing one cubic meter of gas at 20 C. and 1 atm. pressure). Corresponding values for other gaseous hydrocarbons than methane may be readily established by means of the formula e=rnv. /2. The burners according to the present invention are particularly adapted for this principle of operation. The construction of these burners permits the before-mentioned intimate mixing of the two reaction gases. it operated at atmospheric pressure, the load losses in conjunction with these burners are very low, being of the order of 500 kg./m.

The gaseous mixture obtained by means of the herein disclosed process consists of H C0, C0 H 0 and about 0.2% by volume of residual CH It has a H /CO ratio of about 2 and a C0 content of the order of 1% by volume. In view of this composition, and the absence of any gas black, the gaseous mixture can be used directly and without any after-treatment in a second reactor for the manufacture of methanol or of products of the Fischer-Tropsch synthesis.

On the other hand, a second reactor i always a necessity where carbon monoxide must be further reacted in order to produce hydrogen according to the formula when the gas mixture is to be employed in the synthesis of ammonia.

As previously mentioned, the possibility of a partial combustion, at a temperature not above 1000 C. and preferably of about 900 C., of practically pure gaseous hydrocarbons, with oxygen, in the absence of any catalyst and inert gas or steam, and of obtaining thereby a gaseous mixture consisting primarily of CO and H including only about 0.2% by volume of CH, and without the formation of gas black constitutes a substantial improvement over prior art, including applicants prior process disclosed in said Italian patent.

The two reacting gases are pre-mixed and introduced into the oven or reactor by means of one or by several burners, each consisting of a pro-mixer and an outlet tube. According to this invention, the necessary intimate pro-mixing is predicated upon the force of impact and the respective directions of the two gas streams, which must be such as to insure a high level of that component of the velocity which is essential for the impact and the mutual penetration of the two gas streams. Moreover,

two extremely thin streams attain a microscopically uniform composition of the mixed gas stream entering into the burner.

The. herein disclosed novel conception hasbeen con-1 'firmed'by subsequent experiments which prove that the factorsdeterminingthe efficiency of mixing are the value of the tangential'component of the. energy ofthe two flows, the rotational energy and the time of residence of must be produced in order to the mixture in the burner. Exceeding certain energy limits, the second factor prevails over theYfirst. By means of these experiments it has. been; confirmed that, Wlll'l'. burners applying. the above-mentioned principle of pre mixing and with kinetic'energy components of an eifectivje ness as previously set forth, the desired results are readily obtained. 7 7

Referring now in detail :to thejdrawings, thepre-mixers illustrated'in FIGS. 3 and 5"are meant to be appliedto the burneroroutflowtube of FIG. 1; This burner con- 1 sists substantially of theoutflow tube l itself,,applied by means ofa flange 2, to the corresponding flange 2I.or

Z of the pre-mixer shown in FIG'..4 or that of FIG.15,J respectively.. From the pre-mixer the hydrocarbon, for example methane-oxygen mixture,-enters the outflow tube in'the direction of the arrow. Near the front section,v

whichis fastened to the pre-mixentube 1 isprovided with a branch pipe 3 having a safety outlet .4; By means of a partition 5, the from section of the tube is subdivided into several longitudinaL outflow chambers, as shown,

forexample, inthe cross-sectional view of FIG. 2. The rear section of tubel is subdivided'in a similar manner.

by means of a partition 6. However, as indicated in FIG. 2, the walls-of this partition are angularly' offset,

at for. example with respect to the walls of parti tion 5;; .Tube 1 is cooled. by means of a double-wall water;

jacket 7,"having an inlet 8 and an outlet 9 for the cooling water, whereby the walls of the jacket. are arranged so asrto cause the cooling water-to circulate in opposited} rections along the two faces of. interior wall Iii ofthe jacket. V The swirling gasespass from the mixing device: of FIG 3, or that of FIG. 5 to the tube Tube 1 was termed It is attached by the outlet: .of

an outflow tube, above.

the mixing device, and provides the outflow passage'for;

the gas mixture into, thej cornbustion chamber. Tube '1: has an outlet at 100; the gases passing therefrom'intothe 1 combustion chamber or oven or reactor, a wall of which is indicated at 101. As stated above, the two reacting gases; are pre-mixed and introduced into the, oven or re- 11 and 12 .respectively. By means of connecting elbow' pieces 13 and 14 these ports are joined with tubes=15 and 16 which are in axial alignment and are heldat their free extremities by a mixing-chamber. The latter com prises a cylindrical section which is provided'with sleeves. l7 and an annular hollowmember 18 and contains an;

axially displaceable double-coned obturatortor. propore tioning valve19, preferably-madef'of stainlesssteel." shown, this valve'is controlled by a spindle 29, which s Y sion.

ana gesia oppositely, alignedn ducts 11, spectively,.into theisingle peripheral". annular recess 18.

From the latter, the mixed .gasespass throughfconduit j Zll into the outflow tube *1 of the burner. illustrated inv FIG 1. The shape ofdonble' coned member 19 makes the gas'strearns. meet withivelociti'es Shaving substantial and oppositelydirected axial fcomponentsm lnithis way] the. desired mixingis achievedlj Another embodiment ofl'ithe pres-mixer L-is shown :in" FIGS, Sfand .7 6L'f This. mixer comprises; an-inletptube-ZZ; fer-the gas tobeburned, ,,Fitted me this tubelis a-lielical core 23, preferably of stainless-steel, to impart torthe incoming, gas stream a? helicoidal ,rotation9withi:asubstantially high velocity in thetangential planer; Attached.

to tube 22 is an extension 24 of relatively heavy material provided with E a pattern of borings, spaced radially about and longitudinally along thecircumferences: of the 'exten As. shown, ,these (borings 'rarekdrilled at obliqiie 1 angles. through the wall of thisv extension." Oxygen, en-i tering through lateral tube 26into Zthej jacket' 27, is blown r through these borings sothat the tangential. components of the, velocities: of the two gases are directedroppositely'" to, eachfither; whereby the oppositely rotatory flow .of. the two .gases is; gradually damped-f .Obviously, this typen of mixer [also permits asimple control of the velocity, the stream sizeand the impact; angle oftlieztwo gasesg'. thesearethe factors previously mentioned astessentialto this invention. From; the preemixer;the gasesienter.the outflow tube 1 (FIG; 1), substantially without any turbulence, which is importantdn .drderxtdprodiice a regular and undisturbed flainejat the endiof the outflow tubeand.

. Experimentalmixers of the described above types have V been'o'perated atxvelocitiesrangingfrom;;20;..to. 120 in./ sec.- (type: shown in FIG; t3)j:and 'from =15 -i to 1100 r I'm/sec. ;(type: shown in FIG. 5); The load :losses-en-f countered thereby were found to be 475' kg/m As a typical example; the following operative .and con-u structional data are givenz For'; a flow," rate of 300 Nmf/hour o'f CH it suflices if a pre-mixer; orthextype illustrated in PIGQIB has a flow.cross-sectionalareafor- V the two gases of aboutODO'lS in. By shifting theposi-Z. I tion of. obturator valve rarthe' ratio hetweenithe crosssectional: areas.ofpthelflowqof CH4? and O is variedgbut; the sum of these two cross-sectionalareas always remains; V constant. The angleat the ,baseEoftheKdQubIe cone is,;, for example, In case ,of apre-mixer'gof the-type;- illustrated in FIGLS, the volumeof-the- 'Inixingchamber' 3 between the first {and last row Jof borings 25. may va'ry from 900 to 175.0cc;; the borin'gs may have, for example,v

a diameter of 4.1105 mm; each and [heir .num berrm'ay vary 13011140; to 80. Y The residence time lot-the gases; in f the burner is preferably of the. master .O.( )12.jsec. ;The.; flow rates may be so adjusted that, for example,*an-oxygen flow rate offaboutt23i0 Nmf/houn corresponds with an. 'methane'flowyrateiof 300(Nm3lhour. ,Asa rule,,thert ratio of 0 10* (lHiishouldl be.- adjusted at betweenj OQS I and 0.8. v

provided with a thumbscrew Ziltlhziving a scaleiforwarying vthe'sizeof the inlet openings for oxygen-and the hydrocarborrand for indicating the ratio between these openings. Spindle 203s screw-threadedly mountedfor rotation in studs 13% and 140 fixed uponele'rnents S13. and 14 respectively. An indicator sleeve 141 is .carriedin' flangev member: 142, which is fixed upon stud'14tLT By means of this valve, the velocity, stream size and impact" angle of the two gas streams :are readily controlled. Thus the effective. components of the kinetic energyofithe gas, streams, as specified above, can be easily regulated. .T he

- pressure;can be'readilyladapted for operatiodat higher;

double cone li jdeviates,orjdefiects,- thetwo gas jets of oxygen and methane, for example coming from the two When the O .to Cl lggratio is 0. 72, a ratio at; :whichno' carbon black is formed, thestoichiome tri'c equ'ationgof the process maybe summarized as follows]:

' cH -.0.72o =,0 CO+1.66r1 +0. 10co +0.34H2Q In this reaction summary the" small amounts of resid all? methane which, as previously mentionecl arefpresent,;1 an amountof'theQ d I 0f,9-. 2 by yolume based on dry gas; aredisregarded. 1 Underthese-conditions; the amountg;

, of water vapors. formed-in the. gaseous mixtureisequalto 'about':l0 by volumefi.The amount sew-tar. vapors f tends it to decrease when a 05/ CH1? ratioflowerthan $.72.

is employed. I

The Ettore-described prhcss,-carried out atatrnospheric pressure,.-for example, atthe,. pressureiat which natural gas is ayailable, resultingin .a substantial reduction ofthe 13,15 and 12 :14, is :re- V energy requirements for the synthesis of ammonia and methanol.

1 claim:

1. A gas mixer which comprises means providing a chamber, means in the mixer forming separate inlets for two gases to the chamber, a double-coned valve member in said chamber having a stem portion and two opposed joined gas deflecting and spreading surfaces, each of said opposed surfaces flaring outwardly in a smooth and continuous curve from said stem portion to the outermost diameter of said valve member, said chamber having opposite ends communicating with said inlets extending toward each other from the ends, the chamber being enlarged between said ends and provided with opposed valve seats at each end of the enlargement, the enlarged portion of the valve at the outermost diameter of the valve extending into the enlarged portion of the chamber so that each of the opposed surfaces may engage alternatively with a valve seat, the walls of said chamber being shaped to direct the two gases coaxially toward each other so as to impinge on said respective surfaces and so that the impinging of the gases on said surfaces causes intimate mixing, said valve member being mounted for longitudinal movement toward one valve seat and away from the other at any one time for proportioning the relative amounts of said two gases, said chamber having an outlet communicating with the juncture of said two surfaces for conducting out the gas mixture formed.

2. A gas mixer comprising a center section providing a chamber, two gas inlet pipes mounted to form a U with said center section, an axially displaceable valve comprising a double-coned proportioning valve body mounted in said center section, said valve body having a stem portion and two opposed joined surfaces, each of said opposed surfaces flaring outwardly in a smooth and continuous curve from said stem portion to the outermost diameter of said valve body, an enlarged portion of the chamber connecting the ends of the inlet pipes, a valve seat at each of the ends in the chamber, the enlarged portion of the valve stem at the outermost diameter extending into the enlarged portion of the chamber so that each of the opposed surfaces may engage alternatively with a valve seat, said valve body being disposed in said inlet pipes for impinging of said gases on said surfaces in respective zones coaxial with said valve body, a spindle supporting said valve body and disposed longitudinally of and within the base of the U, means on said mixer for turning said spindle to vary the relative sizes of intake openings at the double cone for said gases entering through respective inlet pipes and for indicating the ratio between the said openings, the walls of said chamber being shaped to direct the two gases coaxially toward each other so as to impinge on said respective surfaces and so that the impinging of the gases on said surfaces causes intimate mixing, and a gas conduit communicating with the juncture of said surfaces and extending perpendicularly from said center position.

References Cited by the Examiner UNITED STATES PATENTS 828,086 8/06 Bowers 137-6254 1,480,146 1/24 Bradshaw 48-180 1,490,884 4/24 Spreen 137--625.4 2,252,501 8/41 Foresman 137604 2,742,922 4/56 Frellsen 137625.69 2,838,066 6/58 Harris 137--556 FOREIGN PATENTS 115,513 7/42 Australia.

580,774 9/46 Great Britain.

M. CARY NELSON, Primary Examiner.

MAURICE A. BRINDISI, Examiner. 

1. A GAS MIXER WHICH COMPRISES MEANS PROVIDING A CHAMBER, MEANS IN THE MIXER FORMING SEPARATE INLETS FOR TWO GASES TO THE CHAMBER, A DOUBLE-CONED VALVE MEMBER IN SAID CHAMBER HAVING A STEM PORTION AND TWO OPPOSED JOINED GAS DEFLECTING AND SPREADING SURFACES, EACH OF SAID OPPOSED SURFACES FLARING OUTWARDLY IN A SMOOTH AND CONTINUOUS CURVE FROM SAID STEM PORTION TO THE OUTERMOST DIAMETER OF SAID VALVE MEMBER, SAID CHAMBER HAVING OPPOSITE ENDS COMMUNICATING WITH SAID INLETS EXTENDING TOWARD EACH OTHER FROM THE ENDS, THE CHAMBER BEING ENLARGED BETWEEN SAID ENDS AND PROVIDED WITH OPPOSED VALVE SEATS AT EACH END OF THE ENLARGEMENT, THE ENLARGED PORTION OF THE VALVE AT THE OUTERMOST DIAMETER OF THE VALVE EXTENDING INTO THE ENLARGED PORTION OF THE CHAMBER SO THAT EACH OF THE OPPOSED SURFACES MAY ENGAGE ALTERNATIVELY WITH A VALVE SEAT, THE WALLS OF SAID CHAMBER BEING SHAPED TO DIRECT THE TWO GASES COAXIALLY TOWARD EACH OTHER SO AS TO IMPINGE ON SAID RESPECTIVE SURFACES AND SO THAT THE IMPINGING OF THE GASES ON SAID SURFACES CAUSES INTIMATE MIXING, SAID VALVE MEMBER BEING MOUNTED FOR LONGITUDINAL MOVEMENT TOWARD ONE VALVE SEAT AND AWAY FROM THE OTHER AT ANY ONE TIME FOR PROPORTIONING THE RELATIVE AMOUNTS OF SAID TWO GASES, SAID CHAMBER HAVING AN OUTLET COMMUNICATING WITH THE JUNCTURE OF SAID TWO SURFACES FOR CONDUCTING OUT THE GAS MIXTURE FORMED. 